synchronized method

[Soumy Kumar]

   
Qn in one of the mocks..
 
    public class AQueryClass
    {
        public static synchronized void method1()
        {
            //lots and lots of code here.
         }
 
        public sychronized void method2()
        {
            //lots of code here too.
        }
    }
 
Assuming that all the code inside the method is legal and cannot be a cause for compilation error -
 
 
   1. An attempt to compile will cause a compilation error. Static methods cannot be synchronized.
   2. Compilation will be successfull. The Object instantiated will have a lock which has to be gained by Threads calling any of the two methods.
   3. Compilation will be successfull. There will exist a Class wide lock which will have to be gained by the Thread calling method1 and an instance lock for each instance which will have to be gained by the Thread making a call to method2 on the Object instance. The class wide lock and the instance lock being independent of each other.
   4. Compilation will be successfull. There will exist a Class wide lock which will have to be gained by the Thread calling method1 and an instance lock for each instance which will have to be gained by the Thread making a call to method2 on the Object instance. The class wide lock and the instance lock being mutually exclusive.  

I thought the answer was 4 but its mentioned 3 ...
can anyone clarify ??

[Mike Gershman]

I understand "mutually exclusive" to mean that if you hold one lock, no thread can hold the other lock. This is not true of any locks in Java 1.4.

The correct answer is 3:
"The class wide lock and the instance lock being independent of each other."

[Rubel Ahammad]

mike is right.
static synchronized methods are independent of instance synchronized methods.